Automatic machine for the packaging of products inside bags of plastics

ABSTRACT

The machine is provided with means ( 6, 8, 9, 11″, 13 ) for the controlled feeding of the plastics film to the forming head ( 17 ) which forms with the said film a continuous and descending tubular winding, in which are inserted the products to be packaged by means of a hopper ( 18 ). A heat-sealing unit ( 22 ) performs a longitudinal and continuous sealing (Z) upon the longitudinal and reciprocally superimposed edges of the said tubular winding and downstream of the forming device ( 17 ) sealing and transversal cutting means ( 23 ) perform upon the same tubular winding at least a double transversal continuous tight-sealing, for the head-closing of the filled bag and for the sealing of the bottom of the following bag, while a cut between the two sealing, separates the consecutive bags between them. These means can also comprise an incision device to facilitate the following tear-opening of the bag. The closing of the sealing and cutting means is commanded in advance by the stop of the unwinding of the film of the bobbin, while the elevator platform raises suitably the bag to be closed, to avoid that the edges of the film to be transversally sealed result under stress. When the translation presser ( 34 ) discharges the filled and closed bag from the elevator platform ( 29 ) arrived at the end of its descending stroke, the same platform immediately returns in the high working position, to ensure to the machine a high working speed. An anti-overturning barrier ( 43 ) is provided in the tunnel for the discharge of the filed and closed bags, to avoid that the same overturn toward the discharging pusher, so that this one can freely return in the rest position.

[0001] The invention relates to an automatic machine for the quick packaging of the products inside of bags of plastics formed at the moment, having a proportioned measure with respect to the quantity and/or the quality of the said products and tight-sealed.

[0002] A method and a machine for the packaging of articles with different shapes and dimensions inside of plastics bags, are for example described in the U.S. Pat. No. 5,313,766. This patent describes a machine to be placed in correspondence of the counters of the supermarkets or to be integrated in these, to obtain from a continuous film unwound from a bobbin, bags having a height proportioned to the dimensions and/or to the quantity of the products to be packaged, which at the end of the cycle are closed also on the upper end.

[0003] Currently is spreading the so called “e-commerce” which allows to the consumer to contact via Internet a dealer, to choose the desired products, to effect the transaction in real time with the electronic money and to wait comfortably at home the delivering of the packet with the acquired products. In this type of commerce, the rapidity of the supplying, in addition to the comfort, represents a determinant factor for the success.

[0004] For these reasons it has been developed in the present days a more wide research concerning the means and the processes suitable to reduce to the maximum the delivery times and between these, the times of the packaging of the products, which are the most negatively influential.

[0005] Object of the present invention is to provide a machine for the automatic and quick packaging of the products with various shapes and dimensions in bags formed at the instant and having the dimensions of the products to be packaged. This object is achieved with an apparatus similar to the one described in the US patent above mentioned, but independent from the counter of the supermarket, therefore self-contained and improved to increase the speed and the security of the working cycle and to realise tight-sealed bags, in which preferably remains trapped a correct quantity of air, suitable to form a cushion which protects the packaged products during the phase of the transport to the house of the customer.

[0006] Further features of the invention, and the advantages deriving therefrom, will appear better evident from the following description of a preferred embodiment of the same, made by way of non-limiting example, with reference to the figures of the attached sheets of drawings, in which:

[0007]FIG. 1 is a perspective view of the machine, taken from the side near which is placed the operator and which evidences the upper portion and the bag discharging front from the same machine;

[0008]FIG. 2 shows the machine sectioned transversally at the level of the introduction pit of the products inside the bag during the construction phase,

[0009]FIG. 2a shows laterally and with portions in section constructive details of the inferior portion of the charging hopper of the products;

[0010]FIG. 3 is a perspective view of the group which performs the continuous tight-seal longitudinal welding of the superimposed edges of the tubular winding from which results the packaging bags;

[0011]FIGS. 4 and 5 show other details of the welder of FIG. 3, taken along the respective section lines IV-IV and V-V;

[0012]FIG. 6 shows details taken along the section line VI-VI of FIG. 2 and relative to the guide pit of the bag in the construction phase and to the expulsion means of the formed bag;

[0013]FIG. 7 is a perspective view of the discharging means of the formed bag.

[0014] From FIGS. 1 and 2 it is note that the machine is contained inside a shaped parallelepiped structure 1, having a rectangular base, which bears upon the ground with feet 3 and wheels 4 in order to be, if requested, easily moved and it is superiorly provided, in central position, with a raised portion 101 upon which there opens the mouth of the pit P for the introduction of the products to be packed, which is provided laterally to the said raised portion 101, with bearing planes 201 with the small switchboard 2. The side having greater dimension of the structure 1 at which is disposed the operator, is closed by doors 301 having the shape of an overturned L, and it is provided in its centre with a further door 401, if necessary made of transparent material in order to allow the control of the functionality of the machine and above all useful to allow the removal of a possible trapped bag or to predispose in the correct manner in the formation means of the tubular film wrapping from which the bags are obtained, the same film during the initial phase of pre-arrangement of the machine to the automatic working. On the other side having greater dimensions of the structure 1, is fixed at the bottom and projecting a structure having a rectangular plan 5 which supports, in rotatable manner a couple of rollers 6 parallel between each other and with respect to the greater dimension of the same structure 1, upon which rests the bobbin 7 of the plastics film, guided at the ends by means of housing appendices 105 integral to said structure 5. At least one of the rollers 6 is connected at one end, by means of a positive drive transmission 8, to an electric motor 9 having suitable characteristics, which provides for the rotation of the bobbin 7 in the useful direction for the unwinding of the film 107, to allow to the machine a high working speed (see further).

[0015] Over the structure 5, upon the upper end of the structure 1, is fixed in a projecting manner a rectangular structure 10 which supports a correct number of idle rollers 11 and a pair of oscillating rollers 11′, 11″, all of them parallel to the inferior rollers 6 and the last of which acts as tightening pulley, being provided upon its oscillation fulcrum 12, with a transducer 13 which gives out an electric signal proportional to the angular position of the structure which carries the said tightening pulley and by means of which is controlled the rotation with a proportional speed of the motor 9 for the unwinding of the bobbin 7, the whole in such a manner to ensure a feeding of the film without tensions. The first oscillating roller 11′ is instead controlled by a traction spring 14 placed in such a manner to place on the right or on the left side of the oscillation fulcrum 15 of said roller, to stabilise this latter in the normal operating position indicated in FIG. 2 with the continuous line or in that indicated with the dotted line which sees the same rolling which is in rest against the first roller 11, to retain with this the tail of the film of the bobbin which terminates, in order to facilitate the connection by means of an adhesive strip, with the head of the film unwound from a new bobbin. A suitable outer body 501 covers the structure 10 and it can be used as a working surface.

[0016] The film 107 which comes out from the last transmission roller 11, passes through the transmission structure 16 fixed in projecting manner to the vertical an known type tubular forming device 17, which is fixed at its time with external appendices to the frame of the machine and which, together with said structure realises the forming head, inside of which passes the film from above downwards, in order to form a continuous tubular winding, with longitudinal and superimposed edges which are turned in the opposite portion with respect to the one for the entering of the film, thus on the side of the operator.

[0017] Inside the forming device 17 is placed with correct clearance the hopper 18, the upper edge of which is supported by means of the upper structure 101 of the machine. Both the portions 17 and 18 have a quadrangular section and against the sides of the inferior portion of the hopper act transversal rollers 20 kinetically connected between them and that by means and of a electric motor 21 are actuated upon command to rotate at the same speed, in order to draw downwardly the tubular winding of the film formed in the forming device 17 and with which the same rollers act with contact, in contrast with the support provided by means of little and sprung idle rollers 102 (FIG. 2a) supported by the lower sides of the hopper 18 by means of flat springs 220.

[0018] Before leaving the unit of the forming device and the hopper 17, 18 the longitudinal and superimposed edges of the tubular winding of the film 107, are reciprocally secured each other with a longitudinal continuous heat-sealing operation, realised by means of a device 22 which has been expressly planned for the improved machine which is referred to and that will be further described in the constructive details.

[0019] Below the same unit 17, 18 is placed with the possibility of self centering closure with respect to the vertical center line axis Y of the said unit, the known group 23 which realises upon the film tubular envelope 107, at least a double transverse sealing for the head closing of the filled bag and for the bottom closing of the following bag and which realises a transversal cut upon the portion of envelope which lies between the two consecutive transversal sealings, in such a manner to separate the filled bag from the one which is following.

[0020] Between the unit 23 and the superior unit 17, 18, is provided the horizontal and known support plate 24, connected to the relative screw-nut screw translation system 25, with the motor 26 by means of which the same plate 24 can pass from the position illustrated with continuous line in FIG. 2, in the rest position illustrated with dotted line, and vice-versa. When the plate 24 is in the working position, it supports temporarily the bottom of the forming bag, before the filled bag is discharged from the forming pit.

[0021] Upwardly and downwardly from the sealing and transversal cutting unit 23, there are provided the lateral and opposite folders 27, of the known type, which derive the movement from the unit 23 which carries them from the rest position to a self centering closure position upon the tubular envelope, in correct phase with the intervention of the same group 23, in order to form upon the same envelope lateral and re-entering folds, like a bellows.

[0022] When one bag has been discharged from the forming station, the bag the formation of which has been started in the unit 17, 18 and which has been abandoned by the sealing and transversal cutting unit 23, is left by the inferior plate 24 of temporary support and the bottom of the same bag is supported by means of the elevator platform 29 connected to a screw—nut screw linear actuator 30, supported by the frame of the machine and actuated by the electric motor 31. Upon the platform 29 can be provided known devices to detect the weight of the bag during the filling phase.

[0023] Known barriers with opto-electronic sensors 32, 32′ are provided above and under the forming unit 17, to detect the level of the products inside of the bag at first during the filling phase and later in the phase of closing of the bag. As the bag is gradually filled, the superior optical barrier 32, obscured by the products, controls the descent of the platform 29 up to a predetermined maximum value and controlled by devices which detect the downward travel of the platform 29. When such value is reached, the machine emits a signal which advises the operator of the necessity to command the closure of the filled bag. The operator will complete the filling of the bag avoiding to obscure the upper barrier 32 and then he will command the start of the closing phase of the filled bag.

[0024] It is also provided for a phase of manual operation of the machine according to which the same machine predisposed the empty bag with the maximum height or with the intermediate height required and proportionate to the dimensions of the product to be packaged, without the descent of the platform 29 until the pre-fixed maximum level, then the operator introduces the product in the bag and at last activates the closure phase of the same bag.

[0025] Following the actuation of the closure command of the bag (according to a variant, this phase can be if necessary solved in an autonomous and automatic manner by the machine), the platform 29 descends and stops when the top of the packaged products has gone beyond the optical barrier 32′ with a suitable end stroke. In sequence there intervene the folders 27 for the lateral bellows and then intervenes the welding and transversal cutting unit 23 in order to close superiorly the formed bag, to close inferiorly the following bag and for the reciprocal separation of the two bags.

[0026] A heat-sealing results as more weak as more the edges of the film to be welded to each other are under stress. In order to avoid this drawback, during the transversal sealing phase it is necessary to carefully control the feeding of the film which must not be under stress and which not results too slack because there could be formed folds that could compromise the success of the sealing. To reach these objects it is foreseen that the intervention of the sealing and transversal cut unit 23 begins even prior than that the unwinding motor 9 of the bobbin 7 stops. Together with this solution it is also foreseen that in correct phase the platform 29 which has reached the end stroke position for the upper closure of the filled bag, performs a little stroke in order to ensure the correct slackening of the film also on the lower portion of the unit 23 which in the closing phase has the need to recover the film both upwardly and downwardly.

[0027] All the above mentioned movements must be synchronised and the whole must occur within times which are in the order of tenths or hundredths milliseconds and if this should not occur, there is no certainty that the sealing is done correctly.

[0028] In order to reach these scopes (see FIG. 2), the movement of the sheet-presser sprung bars 123, upwardly and downwardly assembled with respect to the unit 23, not shown in details because are known in the art of heat-sealing, also for the possible delivery of the cooling air jets for the heat-sealed portions, is controlled by means of sensors 62. If the film is too much under stress during the closing of the unit 23, even before that the components of said unit are in reciprocal contact, the said sensors 62 intervene to signal to the microprocessor the necessity to re-establish the correct functioning of the machine. These same means intervene to stop the closing of the group 23 if due to accidental circumstances, during the travel downwardly of the bag, a product should move inside the said bag and should place itself in the way of said unit 23. If this situation occurs, the unit 23 immediately stops the closure movement, re-opens, the platform 29 descends until the upper level of the product is descended adequately under the optical barrier 32′, while a corresponding quantity of film is unwind from the bobbin 7 driven into rotation by the motor 9. Only in a next phase the sealing and cutting unit 23 is carried back in the active working-stroke.

[0029] The formed and closed bag, rests upon the platform 29 and is contained in a pit having a quadrangular section, formed laterally by means of lateral and fixed walls 33, 33′ (see FIG. 6) and formed frontally by a vertical pusher 34 and by a door 35 hinged on a vertical axis 36, pushed in the active position by means of elastic means 37 and which is maintained closed by the co-operation with a lock 38 with which cooperates with its inferior side and which presents an appendix 138 on the plan overall dimensions of the platform 29.

[0030] The pusher 34 is connected to the moving element of a linear and horizontal actuator 39 fixed to the frame of the machine and driven by the electric motor 40. The wall 33 presents a horizontal cut 139 through which passes the connecting bracket of the pusher 34 to the actuator 39, while the wall 33 presents a vertical cut 130 through which passes the connecting bracket of the platform 29 to the actuator 30.

[0031] When the group 23 has finished its phase of sealing and cutting, the platform 29 completes its lowering stroke and disposes itself as shown in the FIGS. 2 and 6, coplanarly or with preference at a level slightly superior to the bottom wall 141 of a horizontal tunnel 41, near to the actuator 39. In the descent end stroke position, the platform 29 co-operates with the appendix 138 of the lock 38 which is opened and pre-disposes the door 35 in the opening phase. In correct phase the actuator 39 is activated and with the pusher 34 pushes the filled and closed bag S to leave the formation pit and to translate in the discharging tunnel 41, while the same bag pushes the door 35 in the opening phase.

[0032] In FIG. 6, with the numeral references 34′, 34″ is indicated the pusher in two successive positions of its expulsion stroke of the bag S and it can be noted that even when the pusher has passed the door 35, this latter is maintained opened by the co-operation with a linear cam 42 made, for example, of “Polyzene” (trademark), fixed in a projecting manner upon the posterior front of the pusher 34. This condition allows the pusher to effect the inverse return stroke in the rest position, without interferences with said door 35. With numeral references 42′ and 42″ is indicated the cam 42 with the pusher in the corresponding positions 34′ and 34″.

[0033] From FIGS. 6 and 7 is noticed that during the phase of expulsion of the filled and closed bag S, the same bag interferes with the rounded arms 143 of a barrier 43, placed transversally in the tunnel 41, which pass through horizontal slots 44 of a lateral wall of the same tunnel 41, which are fixed upon a vertical shaft 243 rotatably supported by means of a fixed structure 343 and that by means of elastic means 443 are usually held in the interception position of the bags being discharged, but that under the pressure of the bag can oscillate toward the lateral wall of the tunnel and disappear in said slots 44.

[0034] The pusher 34 pushes the bag S beyond the barrier 43 and in order to not interfere with the arms 143 of this component, the same pusher is provided with transversal slits 45. When the pusher 34 has gone beyond the barrier 43, this latter elastically comes back in the rest position posteriorly to the bag, preventing the same to fall backwards when said pusher inverts its run to come back in the rest position. Before this phase, immediately after being abandoned by the pusher 24 in its active working stroke, the platform 29 has risen up and pre-arranged for the rest of the new bag in phase of formation and filling, in a manner which allows a high speed of production of the machine.

[0035] During the return of the pusher in the rest position, the elastic means 37 which control the door 35, carry back this component in the position of co-operation with the lock 38 and in a parallel position to the same presser. The details of the lock 38 and of the stop closing rabbets of the door 35 are not shown here, because the same are easily perceivable and realisable by persons skilled in the art.

[0036] At the exit of the machine, the bags filled and closed arrange themselves in single file in a rectilinear channel aligned and in prosecution of the tunnel 41 and from this channel the same bags can be easily taken and carried away by an operator. A sensor, not illustrated, detects the filling situation of the channel 46 and prevents the translation of the pusher to avoid the squashing of the packaged products. According to an embodiment not illustrated, instead of the channel 46 may be provided a conveyer system for the moving away of the bags, particularly suitable when several machines of the kind which is referred to operate in a same place and when the bags must be quickly transferred to the shipping place.

[0037] From FIGS. 2, 3, 4 and 5 it is noted that in the superimposition zone of the longitudinal edges of the film for the bags formation, the hopper 18 is provided with a rectilinear and vertical slit 47 which starts before the superimposition of said edges, in order to allow the entrance inside of the same hopper and then inside of the tubular envelope formed by said film 107, of a small arm 148 downwardly oriented and that with the lower extremity supports a small rectangular base having the role of counter-welder, made of rubber, having a correct thickness, with suitable elastic features and sheathed with “Teflon” (trademark) or equivalent material 248 at least upon the face intended to the contact with the film. With the upper end, the small arm 148 is connected to the fix support 49 with the interposition of vibration-damping member 50 in metal-rubber.

[0038] In contrast to the small base 48 acts the sealing head 51 formed by a metallic rectangular plate, which is covered upon the front toward the film with ceramic material and is provided with vertical and spaced rectilinear projecting parts 151, which touch the same film to form corresponding rectilinear and continuous sealing lines Z. The welder 51 is heated by means of heating resistors housed in the same together with a thermostatic probe and the same welder is fixed upon the edge of a horizontal rod 52 sliding inside a guide block 53 made of suitable material having a low coefficient of friction, on its turn fixed upon the end plate 154 of an arm 54 fulcrumed on a vertical axis 55 supported by means of the fixed support structure 56 provided with an appendix 156 which extends toward the welder and which supports an electromagnet 57 the moving element of which is anchored to an appendix 254 of the arm 54. A helical spring 58 is assembled upon the fulcrum 55 to urge the arm 54 backwards from the counter-welder and to maintain the welder 51 in non-interference position with the film to be sealed when said electromagnet 57 is de-energised.

[0039] The plate 154 supports upon the face opposite to the one which supports the guide block 53, an electric motor 59 with electronic speed control, upon the shaft of which is mounted an eccentric 60 connected by means of the connecting rod 61 to a fork 152 integral to the rod 52 with the welder, which because of said connection is moved with a rectilinear alternate movement to and from the counter-welder 58.

[0040] When the electromagnet 57 is activated and when the welder 51 is in the position of maximum approach to the counter-welder 48, if between these two components should be not present the film, the same components would touch each other, so that the interposed film is subjected to the required compression to ensure a perfect execution of the heat-sealing of the superimposed edges of the film. Against this pressure react with correct rates of elasticity the counter-welder 48, the arm 148 which support it and the vibration dampings 50, in such a manner to avoid breakage of the heat-sealed material.

[0041] When, on the other hand, the welder 51 is in the position of maximum distance from the counter-welder 48, between the two components there is a distance equal or slightly superior to the thickness of the superimposed edges of the film 107 that the same components must seal.

[0042] Good results have been obtained giving to the eccentric 60 a speed rotation of about 1500 revolutions per minute when the tubular envelope of the film to be sealed advances with the maximum speed. The master microprocessor of the machine will provide for the automatic variation of the vibration frequency of the welder in connection with the longitudinal advancement movement of the film, according to laws which can be easily experimented on the machine. All the variables of the longitudinal sealing process, among which the unwinding speed of the bobbin, the instantaneous working temperature of the welder, the vibration frequency of the welder, the approach and removal speed of the welder by means of the electromagnet 57, are controlled and modified automatically by the main control processor of the machine, which ensures the performance of a continuous, uniform and with a perfect seal, also in unexpected working conditions. Only under these conditions it is possible to trap inside the closed bags a quantity of air which is sufficient to ensure a correct protection to the packaged products during the manipulation and the transport of the same bags.

[0043] As shown in FIG. 2, the sealing and transversal cutting unit 23 can be provided under the cutting blade 223 and parallel with this one, with an ancillary and toothed-blade 323, to obtain in the closed bag, under the superior sealing and parallel to this one, some incisions which facilitate the tear opening, also to reutilize the same bag for the household waste collection.

[0044] The machine can be completed with means not shown, in order to carry back upon the bags in formation or already formed, the data relative to the serial number, to the nominative of the client, to the address and/or other, by example with a direct print with ink jet or with an adhesive label, the whole in a manner conceivable and easily realisable by a person skilled in the art. 

1. Process for the packaging of products with thermoplastic and stretchable film, characterized by the following working steps: tubularisation of a stretchable and thermoplastic film unwound from a feeding bobbin, with longitudinal welding of its longitudinal edges, in such a manner to form a continuous tube, arranged almost horizontally and having a transversal section with a width which is suitable for the introduction of the product to be packaged; sealing, with at least one transversal welding, of the head of said film which comes out from the tubularisation and longitudinal welding phase and supporting of the said closed head, in such a manner that the same tube remains in a substantially horizontal position; introduction of the product, inside of the tubular wrapping portion, closed and anteriorly supported, in such a manner to result near to said anterior end of the tubular wrapping; transversal blocking of the wrapping film in a zone which does not touch the product (P); longitudinal stretching of the portion of the tubular wrapping posteriorly blocked, the whole in such a manner that said wrapping portion assumes a length which is superior to the length of the incorporated product, while the same wrapping, because of the reaction to the stretching, tightens transversally on the product and wraps it in a close manner; closing with at least a transversal welding, of the posterior end of the tubular packaging longitudinally stretched, further closing with at least another transversal welding of the head of the tubular wrapping which follows the formed packaging, transversal cutting of the tubular wrapping film in the zone lying between the two said weldings, while the head of the new tubular wrapping is retained, while the tail of the formed packaging is also retained too, while said packaging is horizontally supported and while in correct phase the head of the same packaging is abandoned, in such a manner that the film which composes the same can longitudinally react to close adhere also in this sense to the packaged product; characterized by the fact of comprising the further steps of supporting the transversally closed head which comes out of the tubularisation and welding phase, in such a manner that the same tube remains in a substantially horizontal position; transversal braking of the wrapping film is in a zone which does not touch the product; longitudinal stretching of the portion of the tubular wrapping posteriorly blocked, the whole in such a manner that said wrapping portion assumes a length which is superior to the length of the incorporated product, while the same wrapping, because of the reaction to the stretching, tightens transversally on the product and wraps it in a close manner; interruption of the transversal braking action of the packaging film, in correct phase with the closure of the posterior end of the formed packaging; abandon of the grip of the posterior end of the formed packaging and displacement of this latter from the packaging zone.
 2. Process according to claim 1, in which the length of the portion of tubular film which is longitudinally stretched and/or the amount of the longitudinal stretch of said portion of film, are proportioned to the dimensions of the product to be packaged.
 3. Process according to claim 1, in which there is used thermoplastic and stretchable film, with features of impermeability to gases or presenting the so-called barrier effect and all the longitudinal and transversal weldings performed on the packaging film are tight-seal.
 4. Process according to claim 3, in which in the packaging being formed, before the transversal posterior closing, there is created in the same packaging a modified atmosphere, useful for the conservation of the packaged product
 5. Process according to claim 1, characterized by comprising, prior to the longitudinal stretching phase, an external heating phase of the tubularisation film, a heat flow accompanying the film along the advance direction of the packaging.
 6. Process according to claim 1 in which the heat-sealed transversal portions of the packaging are preferably placed at a lower level with respect to the upper edge of the tray with the packaged product.
 7. Process according to claim 1, characterized by the fact that of comprising an external and sufficiently distributed heating phase of the formed packaging which is left free for the discharge, with temperature values suitable to exalt and uniformly distribute the effects of the elastic retraction of the previously stretched stretch film, in such a manner that the finished packaging results exempt from upper and lateral imperfections, with advantages also of esthetical character.
 8. Machine for the packaging of products with stretchable and thermoplastic film, characterized by the fact of comprising: tubularisation means having an inlet and an outlet, for the tubularisation of a wrapping film taken from a feeding bobbin and means for the longitudinal tight-seal welding of the superimposed edges of such tubularisation film; Means which alternate in the transversal grip of the head of the tubular wrapping which comes out from said tubularisation means, which are pre-arranged for the longitudinal movement of said wrapping, to longitudinally stretch it and to perform on same at least two transversal, parallel and tight seal weldings, a transversal cut placed between the said weldings and to retain the wrapping upstream and downstream of the two welded zones separated by the cut, Means for the cyclical introduction of a product through the inlet of said tubularisation means and up to the outlet of said tubularisation means characterized by the fact of further comprising Means to temporarily support the packaging being formed; Means to brake the forward movement of the tubular wrapping on the discharging mouth of said tubularisation means, to allow the longitudinal stretching of the wrapping in its formation phase, under the action of the active one of said gripping, double welding and interposed cutting means; A conveyor for the taking and the moving away of the cyclically formed packaging.
 9. Machine according to claim 8, in which the tubularisation means for the wrapping film comprise a forming head device in an almost horizontal position, provided with a tubular core with and inlet end and an outlet end and external portions for the tubularisation upon said core of the wrapping film, said device being provided with a section of adjustable amplitude if required and suitable to be traversed with clearance by the products to be packaged which enter from the inlet end of said device from which enters the thermoplastic and stretchable film, unwound from a bobbin and controlled by suitable feeding means and which in its longitudinal traversing of said device, is bent to the shape of continuous tube and its longitudinal edges are superimposed and reciprocally welded with at least a longitudinal seal welding, performed by suitable means placed for example in the lower portion of the forming head device.
 10. Machine according to claim 8, in which means are provided to cyclically arrange a product in front of the inlet end or mouth of the forming head device, where, in longitudinal alignment with said device, there acts a pusher activated by rectilinear alternating motion actuators, which upon command inserts a product to be packaged in the forming head device, accompanying same for a correct length beyond the outlet end or discharging mouth and then moving back to the rest position for the repetition of a new feeding cycle.
 11. Machine according to claim 8, in which the pair of double gripping, double welding and cutting means between the two weldings, placed downstream of the forming head device, transversally to the path of the tubular wrapping film, which means are parallel between them, which alternate in the gripping of the head and of the tail of the packaging being formed, to retain the said packagings and to perform the longitudinal stretching of the packaging which is cyclically in the formation phase, comprise each a preferably upper welding bar, suitable to perform on the wrapping film two parallel weldings in co-operation with a lower bar having the function of counter-welder and comprise means for the transversal cutting of the film, parallelly placed between the means which form the said two weldings, and comprise upstream and downstream of said welding means, means to grip the portion of film subjected to the welding and to retain it also when the said welding bar is by means of suitable means partially moved away from the counter-welder after the execution of the weldings, means being provided to move near and to move away between them the two components of each unit, with a rectilinear and self-centering movement, and means being provided for the horizontal transfer of the same units, firstly closed and moving away from the forming head device, and then open and towards to said device.
 12. Machine according to claim 8, in which the packaging which is cyclically closed in the posterior end, is supported by a comb-shaped horizontal plane, mounted in a projecting manner on the front side of the lower bar having the function of counter-welder for each of said units for the double clamping, double welding and cutting of the tubularised packaging film.
 13. Machine according to claim 8, in which a horizontal and motorized conveyor is provided at the end of the horizontal run of said double clamping, double welding and interposed cutting units, said conveyor being formed, at least in its initial portion by a comb assembly of parallel conveyor belts, between which can penetrate the prongs of said comb-shaped horizontal plane which in correct phase delivers upon said belts the packaging cyclically formed, for its removal from the packaging station.
 14. Machine according to claim 8, in which the means placed over and under the discharging mouth of the tubular core of the forming head device, are made by pressers presenting a rubberized surface which upon command are pushed with the rubber surface against the walls of said tubular core of the forming head device, to block on these the tubularised wrapping film in the phase in which this must be longitudinally stretched by the cyclically active device for the double clamping, double welding and interposed cutting.
 15. Machine according to claim 8, characterized by the fact of utilizing barrier effect stretchable films, and comprising means to create in the packaging being formed, prior to the transversal closing of its posterior end, a modified atmosphere useful for the conservation of the product be packaged.
 16. Machine according to claim 15 in which in the inlet mouth of the forming head device are longitudinally inserted in such position as to not interfere with the product to be packaged cyclically inserted in said device, means supported by external means connected to external operative means and which by using nozzles create in the packaging being formed the required modified atmosphere, with the immission in the packaging of a mixture of gases and/or with the suction of the environmental air.
 17. Machine according to claim 15, in which the pusher which cyclically inserts a product in the packaging station, is suitably shaped and provided with tubular means projecting inside the packaging being formed and connected to blow and/or suction ducts such to promote the formation in the package of the required conservation atmosphere of the product to be packaged.
 18. Machine according to the claim 8, characterized by a slight longitudinal inclination or slope in the run direction of the product to be packaged.
 19. Machine according to claim 8, characterized by the fact of comprising downstream of the film tubularisation means, means for the blow-in of warm air at a correct temperature on the tubularised wrapping while the same moves longitudinally, to better predispose the same wrapping to the subsequent longitudinal stretching and close packaging operation of the inner product.
 20. Machine according to claim 19, in which the blow means for the warm air on the tubular wrapping comprise rectilinear bars, transversally placed, over and under the wrapping which comes out from the forming head device, said bars being placed at a short distance from the film, being provided with a plurality of small holes oriented in such a manner that the warm air delivered by these lick up the film accompanying the same in its forward run, said bars being realized with a thermal insulating material and being connected by means of thermo-resistant ducts to a deviation box in its turn connected to a unit which delivers warm and pressurized air, means being provided for the control of said box to cause it to deliver the warm air to said diffusion bars, when the packaging film runs longitudinally and to cause that the same box commutes to discharge the warm air through an exhaust duct in correct phase with the stop of the longitudinal run of the film and with the intervention of transversal blocking means of the packaging film.
 21. Machine according to claim 20, in which the blow in bars for the warm air on the tubularised wrapping, are placed with a distance from the same wrapping which is comprised between 5 and 20 mm, for example of about 12-15 mm.
 22. Machine according to claim 20, in which the blow-in bars for the warm air are provided with delivery holes with a diameter comprised between 1 and 4 mm and with a distance between centers which is about the double of their diameter.
 23. Machine according to claim 20, in which are provided means to cause that the unit which feeds warm and pressurized air to the deviation box feeds the same air at constant values of pressure and temperature.
 24. Machine according to claim 23, in which at the level of the inlet mouth of the deviation box there is assembled a temperature probe connected to a logic circuit provided with a programming and control terminal and connected to a power interface which electrically feeds the generator for the heating of the air, in such a manner to maintain constant and to the pre-established values the temperature of the warm air produced by this one.
 25. Machine according to claim 23, in which the air is fed under pressure to the electric heating unit by means of a pressure regulator.
 26. Machine according to claim 23, in which the means for the thermo-regulation of the warm air blown onto the tubular wrapping by the blow-in bars are such that the said warm air reaches the stretchable film, if the same has a thickness of about 40 micron, with a temperature which is comprised between 55° and 90°.
 27. Machine according to claim 23, in which the pressure of the warm air fed by the feeding bars which act on stretchable films with a thickness of about 40 micron, is comprised between 0.1 and 1 bar.
 28. Machine according to claim 8, in which the means which transversally block the packaging film in the longitudinal stretching phase of the packaging being formed, operate on the same film upstream of the forming head device.
 29. Machine according to claim 28, characterized by the fact that it comprises parallel and rotatable rollers transversally placed on the packaging film which is still flat, immediately upstream of the forming head device, at least one of these rollers being rubberized, being interested by the film for a wide portion of its circumference and being controlled at least at one end by rotation means with brake or by braking means for example of electromagnetic type, which in correct phase are activated to stop the rubberized roller and to block the longitudinal run of the wrapping film.
 30. Machine according to claim 8 characterized by the fact that the upper component of the double clamping, double welding and interposed cutting units, which alternate upstream and downstream of the packaging being formed, carries a pertinent contrast means which superiorly touches the same package to maintain the same correctly arranged onto the underlying resting means and to ensure a correct deposition on the final discharging conveyor.
 31. Machine according to claim 8 characterized by the fact that it comprises means to externally heat the packaging in the discharging phase on the relative conveyor.
 32. Machine according to claim 31 in which said heating means blow warm air at a correct temperature on the upper portion and at least on the opposite sides of the package in the discharging phase.
 33. Machine according to claim 32 characterized by the fact that the package is made by film with a thickness of about 40 micron, and said heating means blow warm air at a temperature which is comprised between 55 and 90° C., for example between 60 and 80° C.
 34. Machine according to claim 33, in which said heating means rare fed with an air flow of about 20-40 mc/h.
 35. Machine according to claim 32, in which said heating means comprise fixedly arranged diffusers with electric heating grids mounted on the diffusion air openings and comprise means which feed to the same diffusers air with correct values of pressure and flow.
 36. Machine according to the claim 8, characterized by the fact that a general processor controls the functioning of the same and is connected to means which detect the dimensions of the products to be packaged to subordinate to such dimensions the work of all the components of the machine. 